flame Photometric Determination of Manganese in Cement J. J. DIAMOND National Bureau o f Standards,
U. S.
Department of Commerce, Washington
A method for the flame photometric determination of strontium has been extended to the determination of manganese in portland cement and in portland blastfurnace slag cement. The instrument used is the Beckman DU flame photometer with oxyhtdrogen flame and the photomultiplier attachment. No prior chemical separations are performed and the procedure is such that sodium, potassium, strontium, and manganese can be determined flame photometrically on the same sample solution.
T
HE determination of manganese is often included in a c h ~ m ical analysis of cement. Portland blast-furnace slag cement may contain up to 1.5% manganese trioxide (,3). Portland cements, on the other hand, rarely contain more than a few tenths of a per cent of manganese as the trioxide. The manganese in cement is usually determined by the hismuthate or permanganate methods as described in the dmcricm Society for Testing Materials (1) and federal specification ( 8 ) standards for cement analysis. I n the permanganate method the manganese is titrated with standard potassium permanganate solution. The bismuthate method involves oxidation of tlw manganese to permanganate with sodium bismuthatr, and titration of permanganate with standard sodium arsenite solution. The flame photometer is now firmly established as a standard tool for the determination of the alkalies and the alkaline earths. Several investigators have also reported its use for the determination of manganese in various mat,erials ( 7 , 9-11). Because methods are now available for the flame photometric deterniination of sodium, potassium, and strontium in a single I-gram sample of cement (5, 6 ) , it was decided to investigat'e the possibility of determining the manganese in this same sample by the use of a similar procedure. This study was made using a Beckman DU spectrophotometer with model 9200 flame photometer, oxyhydrogen burner, arid photomultiplier attachment. EXPERIMENTAL
It was known that potassium emitted a t a wave length very near that of manganese and might interfere seriously with its determination (4). Preliminary experiments with pure salts showed that a very sharp peak in the manganese emission occurred a t xhout 403.3 mp. Potassium was found t o give a similar sharp peak of much lower intensity a t about 404.5 mp. For metal oxide concentrations up t o 100 p.p.m., these peaks were readily rwolved by the flame photometer, which has a half-intensity band Lvidth of 0.2 mp a t the slit width and wave length used ( 3 ) . There was a slight residual interference of potassium \vit,h the manganese emission, but this was judged to be insignificant for this analysis. I t was necessary to make a correction for background emission due to the other constituents of cement. It was established that this could best be made by determining the emission a t about 401.0 mp, and subtracting it from the emission at 403.3 mp. Because the primary purpose of this study was t o see if a procedure similar t o those already in use for the determination of sodium, potassium, and strontium could be used for manganese, this was tried; no detailed investigation of t,he exact interferences involved n-as made.
25, D. C.
The following procedure was used. One-gram samples of cement were suspended in water, dissolved in 5 nil. of concentrated hydrochloric acid, diluted with m*at,er,digested, filtered to remove the small insoluble residue, and dilut,ed to 100 ml. in volumetric flasks. These solutions were then compared with a series of standards made up from a low-manganese cement of previously determined manganese content. 4 standard manganese solut,ion containing 100 p.p.ni. of manganese trioxide \vas prepared by dissolving 0.3481 gram of electrolytic manganese metal in a litt,le hydrochloric acid and diluting to 1 liter. The metal \vas examined spectroscopically and determined to be better t.han O U . 9 ~ opure. One-gram samples of t,he Ion--manganese cement n-ere treated in the same manner as the sample, and the required volumes of standard manganese solution n-ere added t,o each to give standards containing 10, 20, 40, 60, 80, and 100 p.p.m. of manganese trioside. The comparisons w r e made by setting the %?' dial at 100, atomizing the 100-p.p.m. manganese trioxide standard, and halanring the galvanometer by means of the sensitivity control on t,he monochromator at, a v a v e length of 403.3 nip. .4 cement, solution t,o be analyzed was then atomized, t,he meter balanced by the %2' control, and the per cent transmittance recorded. The wave lengt,h was t,hen set at 401.0 nip, the meter again 1,alanced by means of the %I' dial, and the value recorded. Aft,er a short, rinse with water, the process was repeated one or more times and the readings were averaged. This was then don? for t,he other cements and reference standards. The details of manipulation and other inst,ructions are given in the manufncturers' manuals (3,4). The instrument was set about 1 to 2 turns from the count,erc.loc*!i\\-iselimit of the scnsit,ivity cont,rol on the monochromator, with a slit n-idth of 0.02 mm., zero supprrssion control off, selector sw-itch at .1, and full sensitivity on the photomultiplier battery box control. The manganese line a t 403.3 mp was found to be so sharp that it was not possible to rcset the peak by merely resetting the dial. It, was necessary to reset by slowly varying the Tvave length until maximum signal was obtained, as ohserved by the swing of tmhegalvanometer nerd le.
Table I.
Precision and Accuracy of Results Mnz03, %
Colorimetric 0.049 0 26 Portland blast-furnace slag cement 0 . GO White portland cement (reference standard) 0.013 Sample Portland cement
Flame Photometric Si02 present Si02 absent 0 048 0.050 0.049 0 . 0 4 5 0.25 0.25 0.26 0.26 0 58 0 . GO 0,60 0.60
RESULTS
T o obtain some data on the precision and accuracy of the recommended method of analysis, the manganese was determined in tlvo portland cements and a portland blast-furnace slag cement. The results are shown in Table I. Each of the duplicate flame photometric values nas obtained on a separate sample on different days. These cements were also analj zed colorimetrically as a check on the flame photometric method. This same colorimetric proredure was used to determine accurately the manganese triouide content of a white portland cement, which n a s then used as the low-manganese reference cement in the flame photometric procedure. The colorimetric results shown are the averages of two independent determinations made on different days. The determinations Lvere made on samples with silica present, and from which the silica had been eliminated by a single dehydration with nitric acid. Results were obtained by oxidizing the manganese to permanganate with potassium
328
329
V O L U M E 28, NO. 3, M A R C H 1 9 5 6 periodate in the presence of nitric and phosphoric acids, alld measuring permanganate intensities spectrophotometrically. The data in Table I indicate that the precision and accuracy are satisfactory. Flame photometric determinations made on a samples from which silica had or had not been removed single dehydration n ith hydrochloric acid were equally eatisfucto1 j n-hen cohp:ired with standards similariJ- treated. LITERATURE CITED
(1)
din.
SOC. Testing Materials, Designation C 114-53 (1953).
(2) Ibid., C 205-53 T, 1953.
Beckman Instruments, Inc., Bull. 305A (1954). Ibid.,334 (1954). Diamond, J. J., ANAL.CHEM.27, 913 (1955). Diamond, J. J.. Bean, L.. Ibid., 25, 1825 (1953). Dippel, W. A., Bricker. C. E., Ibid., 27, 1484 (1955). Federal Specification SS-C-158 C, "Cements, IIydrsuli(., 1Iethods for Sampling, Inspection, and Testing," 1952. Kick, H., Z . Pflanzenernaht. Dung.u. Hodenk. 6 7 , 53 (1954). Kakai, Toshio, Ishida. Riydhei, Hidaka, Sakae. J . C'hem. Soc.. Japan, Pure Chern. Sect. 73, 19 (1952). Wever, F., Koch, W., Wiethoff, G., Arch. Eisenhiittenic. 24, 3833 (1953). Accepted December 9 , 1 9 3 .
RECEIVED for review October 6. 1955.
Determination of Water in 1,I -Dimethylhydrazine and Hydrazine by a High Frequency Method ROBERT D. WEAVER, GERALD C. WHITNACK, and E. ST. CLAIR GANTZ Analytical Chemistry Branch,
U. S. Naval
Ordnance Test Station, China Lake, Calif.
The systems water -1,l-dimethylhydrazine and waterhydrazine were studied using a Sargent Model V oscillometer. The data obtained for the two hydrazine systems are presented as plots for the range from 0 to lOO7c water. With the procedure used in this work the results for the range from 0 to 570water in 1,l-dimethylhydrazine indicated an accuracy of 20 parts per thousand. However, in the range from 0 to 10% w-ater in hydrazine the variation of results was too large for analytical application.
ensured constant uniformity of the position of the cell in the holder and also eliminated wear of the plating on the inner electrode. T h e position of the cell holder, relative to the instrument, was fixed by mounting the holder on a large wooclcn platform. The length of the coavial cable connecting the cell holder and the instrument was 6.5 inches. The cells, equipped with Teflon stoppers, excluded atmosphei i i oxygen and moisture satisfactorily. The dial units obtained as a result of measurement depend upon the temperature. T o avoid the effects of temperature drift, the sample cell should be hrld a t the top only, and the temperature of the room should be reasonably constant. Checks of room temperature in this laboratory indicated a total change from morning to night of of water was found t o about 1' C. The temperature be about -30 range dial units per C., which agrees with data in the literature (7, I O ) Between experiments the cell was cleaned with distilled water, then dried with acetone and jet of nitrogen gas through a glass tube drawn sufficientlv small t o pass between the walls of the cell. Care must be taken, when cleaning the cell, not t o wet the external surface ( 7 ) . The cell was filled by means of a pipet which was modified t o deliver about 8.5 in1 , thus filling the cell to 0.5 inch above the plated electrodes Oneounce polyethylene bottles were used as sample containers for the hydrazine solutions.
toe-nt
I-DRhZI?;E or 1,l-dimethylhydrazine from coniiiiei rial sources may contain as much as 4 t o 7% water. There is, a t present, no simple or direct method for the determination of the water content. From the analysis of the hydrazine content by the direct iodate method, water may be obtained by difference (5); however, dissolved salts and ammonia (1-3) may interfeie. .4 direct method of analysis is desirable. T h e anallsis of binary mixtures of water and organic compounds b\. means of high frequency methods has been reported (9, I O ) . The results obtained led this laboratory to investigate the applicability of this method to the analysis of binary mixtui cs of n ater and hydrazine or 1,l-dimethylhydrazine. The theory of high frequency analysis (7, 8) indicates that the analysis of one component of a binary mixture is possible if the ti\ o liquids have sufficiently different dielectric constants. The dielectric constant of water is 80 and that of hydrazine is 55; therefore, analysis of water in hydrazine 11-as thought to be possible by high frequency methods. An estimate of the dielectric constant of dimethylhydrazine by this laboratory v a s less than 10. Therefore, even better possibilities for success evist in this binarv system than in the hydrazine-water APPAR &TUS
A Sargent Model V oscillometer was used throughout this study with a small cell of the test tube type and an appropriate cell holder. T o improve stability of operation, the Center Adjust condenser was mounted firmly on a rigid bracket and the ground lugs attached t o each fixed range sm-itch condenser were soldered to the common ground wire that runs parallel t o the lugs. The instrument then proved t o be stable following a 1.5hour warm up. Drift was less than 5 range dial units per hour and minor mechanical vibration had no adverse effects. This laboratory found, as have others ( 7 , I O ) , that the position of the cell in the holder influences the reading obtained. This Fas overcome by inserting a banana plug into the bottom of the cell and a banana jack into the cell holder. These modifications
PURIFICATION OF HYDRAZINE .4ND DIMETHYLHYDRAZINE
The hydrazine was obtained from Fairmount Chemical Co., Sewark, K.J., and assayed 95%. After purification by vacuum distillation from fused potassium hydroxide ( 1 ) the assay was 99.89$ hydrazine ( 6 ) . The distillate was stored in a refrigerator in a borosilicate glass flask. The ground-glass stopper of the flask was sealed with "para gum-rubber" (Central Scientific Co.) tape and with clear plastic spray over the surface of the tape. The 1,I-dimethylhydrazine wa.9 obtained from Aerojct-General Corp., Azusa, Calif. 1,l-Dimethylhydrazoriium2,2-dimethylcarbazate
CI-T., \
H
/
s--s 0 / \"
CH,
C-OH.DMH
was identified as being prescnt in some lots of the dimethylhydrazine. This compound sublimes at about 57' C., collects in the condensing head of the column during atmospheric distillation of the dimethylhydrazine, and is slowly washed into the receiver by the condensate. T o eliminate this contamination, the top of the column was fitted with a three-way stopcock having a bore opening of 0.5
